(Motorsport-Total.com) – In the run-up to the new Formula 1 season, the discussion centered not only on energy management but primarily on one word: compression ratio. Simply put, this is the ratio between the volume of the cylinder when the piston is at bottom dead center and the volume at top dead center. To make the 2026 engine formula more accessible to newcomers and to facilitate work with fully sustainable fuels, the limit was lowered from 18:1 to 16:1.
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The issue became political when competitors got wind that Mercedes was able to comply with the 16:1 limit during static tests at ambient temperature, but could achieve a higher ratio during operation. This is potentially related to the material expansion of pistons and connecting rods. It should be noted that today’s reality is far more complex than just the material itself, as these components often consist of numerous layers using advanced 3D printing techniques.
An important nuance is that it was often prematurely assumed that Mercedes would reach the full 18:1 of the previous era during operation, while in reality, the difference seems to be far more subtle. Nevertheless, the rivals – led by Audi – were determined to eliminate this perceived advantage by sending a joint letter to the world governing body FIA, together with Ferrari and Honda.
Why did the FIA initiate a vote?
After a meeting of technical experts on January 22, the FIA initially saw no need for changes, but the picture gradually changed. This may have been the result of political pressure, but according to Nikolas Tombazis, the FIA’s single-seater director, it was primarily due to another factor: the way the regulations were written was not robust enough to achieve the goal.
“There are many nuances when discussing such a matter, because there is what the regulations intend. Maintaining the compression ratio at 16:1 was one of the core objectives when the regulations were discussed with the manufacturers in 2022,” Tombazis said when asked by Autosport, a sister publication of Motorsport-Total.com.
“And then there is the issue of what exactly is in the regulations. It became obvious that with what was in the regulations, there could be ways to achieve a higher compression ratio,” Tombazis continued.
Both sides could refer to different parts. Article C5.4.3 stated that the compression ratio is only measured at ambient temperature. Mercedes’ rivals were able to strengthen their position with the more general Article 1.5, which states: “Formula 1 cars must comply with these regulations in their entirety at all times during a competition.” Since the compression ratio of 16:1 is explicitly in the regulations, these manufacturers argued that all engines must comply with this value at all times.
Basically, both sides had valid arguments, which meant that the FIA’s main goal was to tighten the wording of the regulations to remove any ambiguity.
“When rules need to be improved because they don’t fully achieve the goal, we try to make changes. We want the rules to remain focused on the goal and not evolve incrementally when interpretations may have stretched them a little in one direction or another,” says Tombazis.
A compromise even Mercedes can live with?
The follow-up question, of course, is what an acceptable compromise would look like. The FIA had to actively search for one, as any change required a qualified majority in the Power Unit Advisory Committee – which in practice means four of the five engine manufacturers plus the FIA and Formula 1 management.
In its statement, the FIA announced that the proposal was accepted unanimously, implying that even Mercedes can live with the end result. This may sound surprising – especially since the change will now take effect on June 1 instead of August 1 – but Toto Wolff had already hinted at this in Bahrain.
“I think the way it’s been done now is that it has to comply with the regulations when it’s cold and when it’s hot, so it doesn’t give anyone an advantage,” Wolff said. “I think the other guys’ attempt was to have it measured only when hot, so they could actually have it outside the regulations when cold. Now it’s a fair game for everyone.”
The fact that there will be a double measurement – one cold and one at 130 degrees Celsius – was crucial for Mercedes. It prevents competitors from doing more or less the opposite of what Mercedes is doing. The manufacturer with the star achieves a higher ratio when the engine is hot, while the ratio normally drops slightly as the engine warms up.
Some competitors would therefore have preferred a pure hot test. In this scenario, they could comply with the 16:1 limit at 130 degrees Celsius, but theoretically achieve a higher ratio at lower temperatures. With the adopted solution, this possibility is excluded, which is why Wolff called it “a fair game” on both sides.
The current result is a prime example of a Formula 1 compromise. By bringing the date forward from August 1 to June 1, the FIA ensured that Mercedes’ rivals could agree. At the same time, the decision to maintain a double test for the rest of the year means that Mercedes has also partially achieved its goal. Both sides have gained something in this debate.
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Should a manufacturer need to make adjustments to its internal combustion engine to comply with the new procedures, the technical regulations provide scope for this – although everything falls under the budget cap for engine manufacturers. From 2027, the compression ratio will only be measured with a hot engine, but by then all manufacturers will have had enough time to adapt.
Are there still bigger problems to solve?
For the FIA, timing was crucial – and that perhaps applies to everyone involved. The governing body said from the start that it felt the discussion had been blown out of proportion and was determined not to let it overshadow the season opener in Melbourne.
“People are getting a bit too excited, and I don’t think this issue ever deserved this level of attention,” Tombazis said. “I’m not saying it’s not important, but does it deserve all this excitement over many months? Honestly, no.”
The FIA wanted to draw a line under the matter before traveling to Melbourne – a priority that was also recognized by the engine manufacturers, including Mercedes.
“We were quite relaxed about even having a protest running in Melbourne on Friday, but is that what we want?” Wolff asked the rhetorical question of whether this would be in the best interest of the sport.
“We’ve said all along that this looks like a storm in a teacup, the whole thing. Numbers came up, if those numbers had been true, I would have absolutely understood why someone would fight it. But in the end, it’s not worth the fight,” the Mercedes team principal concluded.
